This invention relates to quick-attaching couplers for three-point hitches on agricultural tractors and more particularly to quick-attaching couplers which include powered adjustment.
A conventional agricultural tractor has a three-point hitch which is designed to connect an implement to the tractor and permit the tractor to raise and lower the implement. With a typical three-point hitch, an implement is supported at three points by a pair of lower links and a central upper link. The lower links are pivotally raised and lowered by lift arms connected to powered shafts at the rear of the tractor. The lower links control the raising and lowering of the implement between its working and transport positions. The central upper link has a forward end which is pivotally connected to the tractor and a rear end which is adapted to be connected to the implement to stabilize the implement in pitch. The central upper link is usually adjustable in length to permit fore and aft pitch adjustment of the attached implement. The central upper link normally includes a turnbuckle to perform manual adjustment of the link.
The length of the upper link is extremely important in certain operations such as cultivating where the cultivator must penetrate the soil at a specified depth in order for the cultivator to perform properly. An operator normally will attach the implement to the three-point hitch and estimate the proper length of the upper arm to obtain effective operation of the implement. The operator then travels across the field a short distance to observe the operation of the implement. If the length of the upper link is incorrect, the operator must stop the tractor, dismount the tractor, manually adjust the length of the upper link, and remount the tractor. This sequence may be repeated several times in order to obtain the correct length for the upper link. Constant dismounting and mounting of the tractor is extremely inconvenient and burdensome. In addition, the soil conditions may vary during the cultivation of a particular field which will affect the performance of the cultivator. Therefore, the operator also may need to adjust the length of the upper link during the cultivating operation.
Quick-attaching couplers have been known to those skilled in the art to eliminate the time consuming process which is required each time the operator wishes to attach a different implement to the tractor. A conventional three-point hitch requires the operator to dismount the tractor and manually attach the two lower links of the three-point hitch to the lower hitch studs of the implement. The operator must also attach the central upper link of the three-point hitch to upper hitch point of the implement by inserting an upper hitch pin. Finally, the operator must insert locking pins into the lower hitch studs and the upper hitch pin. This procedure can be time-consuming and burdensome whenever the operator is attaching an implement.
A quick-attaching coupler can be used to quickly attach implements to the tractor without manual attachment of the lower and upper links of the three-point hitch to the implement. The quick-attaching coupler is essentially a frame which has three hooks extending rearwardly and which is premounted and carried on the outer end of the three-point hitch. The coupler is attached to the three-point hitch in the same manner as an implement would be attached to the three-point hitch. The tractor with the quick-attaching coupler is then connected to the implement. The operator lowers the three-point hitch and positions the hooks on the coupler below the lower hitch studs and the upper hitch pin on the implement. The operator then raises the three-point hitch whereby the hooks on the coupler engage the implement hitching points. Occasionally, the operator must dismount the tractor in order to manually adjust the length of the upper link so that the coupler will engage the upper hitch point.
In order to reduce operator effort and permit adjustment of the hitch during various operations, there have been suggestions to provide a power operated device to adjust the length of the upper link. For example, U.S. Pat. No. 3,561,789 discloses an adjustable length upper link which may be in the form of a hydraulic cylinder or an electric motor configuration. The hydraulic cylinder or electric motor configuration is substituted for the conventional upper link which contains a turnbuckle. However, these designs require the operator to remove the upper link and install the hydraulic or electric adjustable length upper link. When the operator wishes to use the conventional upper link, the operator must remove the hydraulic or electric adjustable length upper link and install the conventional upper link.
One object of this invention is to provide a quick-attaching coupler which has angle adjustment.
Another object of this invention is to provide a quick-attaching coupler which enables the operator to adjust the angle of the implement hitch connection during the tillage operation so that the implement performs effectively.
Another object of this invention is to provide a quick-attaching coupler which enables the operator to adjust the angle of the coupler so that attachment and removal of the implement is less difficult and does not require dismounting the tractor.
Another object of this invention is to provide a quick-attaching coupler with angle adjustment which does not require the removal or replacement of the upper link of the three-point hitch.
Another object of this invention is to provide a quick-attaching coupler with angle adjustment which is rugged in construction, economical to manufacture and efficient in operation.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.